The Radiation Core Facility is designed to provide access to radiation sources and expertise for PO-1 investigators. The facilities are located in the Chamberlain labs of the University of Pennsylvania, within the Department of Radiation Oncology?s Research Division. This resource is centrally located and accessible to all investigators. The Radiation Core is comprised of a low dose rate (1.6 Gy/min) Cesium irradiator (JL Shepherd Mark I Model 68a), a high dose rate (10.6 Gy/min) Cesium irradiator (JL Shepherd Mark I Model 30) and an RT250 (Phillips) therapeutic orthovoltage x-ray cabinet. A research associate provides training and technical assistance with the use of this equipment. Service contracts funded by the core serve to maintain and repair the equipment when needed. The core leader, Dr. Richard Maughan, is the director of Medical Physics which includes Engineering for the Department of Radiation Oncology. He consults with investigators on questions relating to dosimetry and shielding and he and his staff provide on-site assistance in the event of malfunctions.